A micro-milling study of Al-4043 workpieces built using wire arc additive manufacturing (WAAM)

Abstract

Wire arc additive manufacturing (WAAM) is a direct-energy deposition, metal additive manufacturing process. Due to the thermal cycling of the workpiece between deposited layers, microstructural variations exist, which are otherwise not present in traditional metallic workpieces. The microstructures present within the workpiece have a profound effect on the mechanical properties of the workpiece. Traditionally, expensive and time-consuming micro- and macro-scale characterization techniques such as microscopy and mechanical testing have been used to gain insight into the microstructure present within workpieces produced using WAAM. This Thesis researches the correlation of the microstructural variations of aluminum 4043 workpieces produced using WAAM and their micro-machining responses. Characterization of the workpiece material is conducted through optical microscopy and hardness testing. A strong correlation between microstructural variations and micro-machining responses including cutting force, machined surface roughness, burr formation, and tool wear is observed. Hardness, cutting force, surface roughness, and tool wear all show an increasing trend with an increasing second dendrite arm spacing (SDAS) of the workpiece material. Results from the burr formation show a decreasing trend as SDAS coarsens within the workpiece material. These results indicate that micro-machining responses are sensitive to the microstructure seen in WAAM-produced parts. Subsequently, the development of a hybrid manufacturing cell is proposed as a future research direction.